The present invention is related to a hot/cold water tube connection structure for plastic faucets, comprising a hot/cold water connector tube made up of a valve seat and a coupling tube wherein the valve seat has a screw tube with engaging rings that can be securely locked to a coupling joint with an internal screw thread section of the coupling tube to provide a separate type of design thereof which can not only achieve securer connection structure to avoid the problem of gaps found in the conventional tube connection structure, but also facilitate an easier replacement thereof for economical efficiency and eco-protection purpose.
Please refer to FIGS. 1 to 2 inclusive. A conventional plastic faucet 10 includes a hot/cold water connector tube 11, 12 made up of a valve seat 13 (referring to FIG. 2) that is injection-molded to integrally combine with a metallic outer tube 111, 121 having a screw thread section defining thereon and form a plastic-and-metallic bound inner tube 112, 122 at the inner wall thereof. Due to the principle of hot-expansion and cold-contraction thereof, the processed inner tube 112, 122 after cooling off tends to get shrunken inwards and fail to keep an even surface with the end edge of the outer tube 111, 121 thereof. As a result, when a screw joint 21 of a water inlet tube 20 is coupled with the outer tube 111, 121, a water-sealing hoop 22 mounted at the screw joint 21 can simply abut against the end surface of the outer tube 111, 121, which, relatively reducing the sealing off area thereof, can hinder the connection structure to positively resist the water pressure and may lead to the problem of water leakage thereby. In addition, the deformed inner tube 112, 121 shrunken after the cooling off process thereof can also affect its combination with the outer tube 111, 121 with a gap A revealed there-between and result in a poor connection structure thereby. And, the hot/cold water connector tube 11, 12 is injection-molded of the inner and outer tubes 112, 122, 111, 121 and integrally combined with the valve seat 13 into one unit. In case the valve seat 13 is worn out of use, the hot/cold water connector tube 11, 12 must also be replaced along with the valve seat 13, which is not only uneconomical, but may increase the burden to the environment.